3G OREODOiV. 



an iiTognlar oblique line from the antero-inferior angle of tlie malar bone, opposite 

 the position of the second true molar, to the angular process of the os frontis at some 

 distance posterior to its tcrminaticm. 



The malar bone below the orbit externally, presents a single, smooth, convex 

 surface, slightly directed upward. Its inferior margin is thick, strong, and rough- 

 ened; and its posterior extremity beneath the position of the post-orbital arch, is 

 deeply notched for the reception of the anterior extremity of the zygomatic pro- 

 cess of the temporal bone. 



The intermaxillary bone, compared with that of recent ruminants, or of the Auo^jIo- 

 therium, or even with that of carnivora, is very small but strong. Its upper extre- 

 mity is received into a notch of the maxillary bone, and does not come into con- 

 tact with the nasal bone. 



Inferior Maxilla.— (PL II. Figs. 1, 3; IV. 4 ; VI. 4, 6.) The lower jaw is inter- 

 mediate in its form to that of the extinct A)ioplotherium and the common Hog, 

 except that the alveolar margin, at its anterior extremity, is not everted as in the 

 latter, but retains the upward direction, as along the course of the molar alveoli. 



The body of the bone, compared with that of the Deer, is relatively deep, and 

 its base pursues a less sigmoid course, and is very like that of Anqplotherium Its 

 outer side is vertical, and very slightly convex, but anterior to the mental foramen 

 is convex forward, or rapidly convergent to the symphysis. Its thickest part is 

 along the line of the latter, and that of the alveoli. 



The symphysis is deep, and forms a strong slope; but it approaches the vertical 

 line much more than in the Axoplotherium, or than in the Hog. Its lower part, or 

 the posterior mental tubercle, is on a line perpendicular to the second premolar, or 

 in some specimens to the interval between this and the third. 



The alveolar margin ascends so rapidly posterior to the last premolar, that the 

 body of the lower jaw behind the last molar, is deeper by more than half than it 

 is below the former tooth. 



The ramus is relatively as broad as in the Hog, but is more vertical and convex 

 upon its outer face. It is relatively deeper than in Anoplotlierium, but is less pro- 

 duced backwards than in this, and more so than in the Hog. The posterior mar- 

 gin is thick and convex, and projects externally into an irregular ridge for the 

 masseteric attachment. The inner side of the ramus inferiorly presents a concavity 

 which converges forward below the molar alveoli. Below the notch separating 

 the condyle and coronoid process the external surface presents a depression in form 

 like that of the Peccary, but deeper, in the possession of which Oreodon differs 

 from all recent ruminants. 



The coronoid process, in comparison with that of the latter, is remarkable on 

 account of its shortness, being relatively not longer than that of the Hog, which it 

 also resembles in form and relation to the condyle. The latter is a transverse 

 convexity, very slightly inclining downward within, and possesses about the same 

 extent and form as in the Peccary. 



The anterior mental foramen is placed below the second premolar, or the interval 

 between it and the first. Not unfrequently there is a second, or even a third, but 

 smaller foramen, situated at variable distances posterior to the principal one. 



